US2269157A

US2269157A - Automatic fluid fuel burner control

Info

Publication number: US2269157A
Application number: US348949A
Authority: US
Inventors: Samuel J Levine
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1940-07-31
Filing date: 1940-07-31
Publication date: 1942-01-06
Anticipated expiration: 1959-01-06

Description

Jan. 6, 1942. s. J. LEVINE I AUTOMATIC FLUID FUEL BURNER CONTROL Filed July 31. 1940 PILOT BURNER HNN BURNER Inventor: Samuel J. Levine,

y His Attorney Patented Jan. 6, 1942 v i I UNITED STATES PATENT OFFICE AUTOMATIC FLUm FUEL BURNER CQNTROL Samuel J. Levine, Verona, N. .L, assignor to General Electric Company, a corporation of New York Application July 31,1940, Serial N... 348,949

Claims. (Cl. 158117.1)

This invention relates to a control system for a call for heat by a control device and to embody a fluid fuel burner of the type having a main into such a system safety control features which burner and a normally out pilot burner for ignitwill give more complete protection against the ing the main burner, an igniter, motor-operated escape of large quantities of unburned fuel and valves for controlling the main burner and pilot 5 the resultant danger of explosion upon the ocburner, and a relay switching system for concurrence of abnormal operating conditions.

trolling the operation of the main burner and More specifically, it is an object of my invenpilot burner valve motors. In this type of control tion to provide a control system for afluid fuel system'it is common to provide a combustion reburner adapted to prevent the escape of unburned sponsive device associated with the pilot burner fuel from the main burner in the event of pilot which operates a control device to prevent the gas failure, pilot flame failure, or igniter failure energization of the main burner valve until comcaused by abnormal operating conditions includbustion occurs at the pilot burner. This is acing momentary dips in fuel pressure-and electricomplished by connecting the control device to cal supply voltage.

energize the pilot burner in the start" position It is a further object of myinvention to proand the main 'burner in the run position. This vide a control system of the type described which prevents the possibility of a large quantity of unwill be positive in operation, give a maximum of burned fuel from escaping from the main burner protection and which will be cheap to manufacand the resultant danger of explosion in case ture and install.

the pilot burner should fail to ignite for some m Further objects and advantages of my invenreason dining the starting operation of the tion will become apparent as the following deburner. It has been found, however, that these scription proceeds, and the features of novelty combustion responsive devices do not give comwhich characterize my inv n w e Pointed plete protection upon the occurrenceof certain out with'particularity in the'claims annexed to abnormal conditions. For example, assume that and forming a part of this specification.

the burner is running normally and the main 1 My invention will be better understood from I burner is energized. The fuel pressure may then the following description taken in connection with dip sufliciently to put out the pilot and main the accompanying drawing, in which the single burner and then immediately return to normal. figure illustrates, in schematic form, one embodi- Due to the fact that the combustion responsive 3i ment of my invention.

devices often used, such as one. of the thermal Referring now to the drawing, the main burner type, require a considerable time to return to the II of a fluid fuel burner, illustrated only schestart" position upon a cessation of combustion, matically, is supplied with fluid fuel through a a large quantity of unburned fuel may escape conduit ll connectedtothe inlet conduit l2 which before the main burner is deenergized. is connected to any suitable source of fluid fuel Likewise, in systems using electrically operated not shown. The conduit H is provided with a motors to open the control valves, a sudden dip normally closed valve l8 operated by any suitable in supply voltage during operation of the main electrical actuating means such as a solenoid mo- .burner may cause the valves to drop closed for a tor ll. The pilot burner I! is supplied withfuel sufiicient time to put out the pilot and main throushaconduit whichis connected with the burner but then immediately open them upon a fuel supply conduit II. The pilot burner conreturn of the voltage to normal. Here again a duit I is likewise provided with a normally closed large quantity of unburned fuel may escape from valve I! operated by a Suit ble el tric l ctu tthe main burner before the combustion responing means such as a solenoid motor l8. sive device can return to the start position The pilot burner is of the normally out yp and deenergize the main. burner. Also, in control that is, the pilot burner is on only when the circuits where the valve motors are energized burner is in operation. This arrangement of the through a circuit including a control switch such pilot burner is desirable because of the saving as a thermostat, a manual manipulation of the in fuel cost butsom'e me ns m be Pr v thermostat has the same effect on the system as M for lighting pilot burner when the burner is avoltage dip described above. started. To accomplish this I have provided It is an object of my invention to provide an an electric igniter I! of the hot wire type the automatic control system for a fluid fuel burner connections of which will be described below. It

which will automatically control the operation of is obvious that other well-known types of electric the pilot burner and main burner in response to isniters, a platinum sponge, or a constantly burn- A trolled by any suitable combustion responsive device 22. I have shown at 22 a combustion responsive device of the thermal type comprising a thermostatic bulb 23, located adjacent'the pilot burner l5, connected to a Sylphon bellows 24 by a tube 25. The bulb 23 is located so that it is not appreciably afl'ected by the heat generated by the igniter l9. The Sylphon bellows operates the switching means 2|through a member 26. Any other suitable form of combustion responsive device might be used to operate the switching means 2|.

The valve motors l4 and I3 and the igniter |9 are supplied with electrical energy from the secondary winding 30 of the transformer 28 having its primary winding 29 connected to a suitable source 21. The motors l4, l8, and igniter |9 are controlled by switching means the action of which will now be described.

In the drawing the control apparatus is shown in the "off position. When the control switch 20 is closed such as by the movement of the bimetal member 33 of a thermostat to the left closing contacts 3|, 32 in response to a call for heat in a zone heated by the burner, the pilot valve motor and igniter are energized through the switching means 2|. valve motor may be traced from the secondary 30 of the transformer 28 through line 34, thermostat 28, line 36; contact 31-a, bridging member 31, contact 31b, line 40, pilot valve motor |8. line 35 back to secondary 30. The circuit to the igniter may be traced from secondary 38 to contact 31b as described above, line 4|, contact 38-b, bridging member 38, contact 38a, line 42, igniter l9, line 35 back to secondary 30. The pilot valve motor being energized the valve I1 is opened and fuel is discharged from the pilot burner l and lighted by the energized igniter I9.

It will be noted that I have provided a holding circuit around contacts 31-a, 31-b, controlled by a switch 43. The switch 43 is actuated in response to a predetermined fuel pressure in the pilot burner conduit l6. To accomplish this I have illustrated the switch 43 connected by a member 45 to a diaphragm 44 movable in response to the pressure. in chamber 46. The chamber 46 is connected to conduit l6 through a tube 41. When pilot valve |1 opens, the pressure in conduit I6, and consequently chamber 46, increases forcingdiaphragm 44 upwardly thereby closing switch 43. The switch 43, when closed, shorts out the current path through bridging member 31 of switch 2|. The switch is arranged to open when the fuel pressure in conduit decreases to a value slightly greater than that required to maintain combustion at the pilot burner. Thus the switch 43 will open the electrical circuit before the pressure in conduit I6 is reduced to a point where the pilot will go out or is so reduced in size that it will not ignite the fuel issuing from the main burner.

After combustion starts at the pilot burner I5 75 niter.

The circuit to the pilot.

the fluid in thermostatic bulb 23 becomes heated and expands causing the Sylphon bellows to move upwardly thereby causing the

bridging members

31, 38, and 39 of switch 2| to move to the run" position indicated by the dotted lines. The opening of the contacts 31-a, 31-b has no effect on the control circuit since the energizing current passes through the holding circuit closed by switch 43. However, the opening of contacts 38a, 38-11 breaks the circuit to the igniter thereby deenergizing the same. The closing of contacts 39-a, 39-11, by the bridging member 39 completes the circuit to energize the main burner valve motor l4 thereby causing the opening of the valve and a flow of fuel to the main burner which is then ignited by the pilot burner. The circuit to the main valve motor |4 may then be traced from the transformer secondary 38 through line 34, thermostat 23, line 36, switch 43, lines 40 and 4|, contact 39b, bridging member 39, contact 39-a, line 41, solenoid motor 4 and line 35 back to transformer secondary 39.

When the thermostat 28 is satisfied the contacts 3|, 32 open deenergizing the pilot burner and main burner valve motors l8 and I4 and allowing the valves l1 and I3 to close thus turnin 01! the burners. valve |1 causes an immediate decrease of the pressure in conduit l6 and hence pressure chamber 46 thereby causing switch 43 to open. Subsequently the thermostatic bulb 23 cools down and gradually the Sylphon bellows contracts causing the bridging

members

31, 38, and 39 of switch 2| to return to the start position. The control apparatus is then ready for another cycle of operation. a

The operation of my control system may be summarized as follows:

Upon the closing of the control switch or thermostat 20 the pilot valve I1 is opened its motor |8 being energized through switch member 31. The igniter I3 is also heated being energized through switch members 31 and 38. As soon as pilot valve l1 opens, switch 43 closes since the gas pressure builds up a chamber 46. When the igniter reaches sufllcient temperature, the pilot gas ignites and heats up the thermostatic bulb 23 causing the bellows 24 toexpand opening switch members 31 and 38 and closin 39. Thus the igniter is deenergized and the motor I4 is energized opening the main burner valve. Fuel entering the main burner is then ignited by the pilot burner.

When the control switch or thermostat 20 opens, it deenergizes motors l8 and I4 closin valves l1 and I3 which turn oil the gas supply to both the main and pilot burners. Pressure switch 43 then opens due to the drop of fuel pressure in conduit l6 and finally when the thermostatic bulb 23 has cooled sufilciently, switch members 31 and 38 close and 39"opens. This completes a cycle of operation.

Because of the time required for the combustion responsiv device 22 to operate it is necessary to protect against abnormal conditions of 1 operation such as voltage and fuel p7 -Jsure dips bumed fuel would escape from the main burner until combustion responsive device 22 could return to the start position and energize the ig- The ignition then of a large quantity The closing ofthe pilot burner age dip which causes the pilot valve ll to close,

because of deenergization of its control motor l3, will drop the gas pressure in conduit 16 sufficiently to open pressure switch 43. Return of voltage to normal cannot then re-open the pilot or main valve until the combustion responsive device 22 returns to the start position and closes switch member 31 to recycle the operation of the control system. Manual operation of the switch 20, which produces the effect of a voltage dip is also protected against in' a similar manner.

Likewise a pressure dip of suflicient magnitude to put out the pilot will open pressure switch 43. This will result in closure of the main and pilot burner valves and upon a rise in pressure of the fuel no unburned gas can escape until the recycling operation is completed. Thus the provision of a single operating means, namely, the pressure operated switch 43, operates to give protection against both supply voltage and fuel pressure failure.

Also it is evident if during th starting operation the pilot rails to ignite for some reason P main open upon a closure of control switch 20 but the amount of unburned fuel escaping from the pilot is so small that no dangerous condition is likely to result.

While I have shown and described a specifi I embodiment of my invention, it will become apparent to those skilled in the art that my invention has other applications, and that changes and modifications may be made without departing from the spirit and scope of my invention. Ltherefore aim in the appended claims to cover all such modifications and changes.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In afluid fuel burner control system, a main burner connected to a fuel supply source by a main burner conduit, a normally closed valve interposed in said main burner conduit, a pilot burner connected to said fuel supply source by a pilot conduit, a normally closed pilot valve interposed in said pilot conduit, electrically actuated opening means for the burner valve, electrically actuated opening means for the pilot valve, means for igniting the pilot burner, an energizing circuit for the main valve and pilot valve opening means, a first switch in said energizing circuit, a second switch for controlling the energization of said main valve opening means, heat responsive means associated with said pilot burner for controlling said first and second switches, said heat responsive means being normally at a start position in which said first switch is closed and said second switch is open and moving to a run position in which said first switch is open and said second switch is closed in response to combustion at the pilot burner, a holding circuit shunting said first switch, said holding circuitincluding a normally open pressure switch and means for closing said pressure switch upon the attainment of a predetermined fuel supply pressure in the pilot conduit between the pilot valve and the pilot burner whereby upon a falling of said pressure below said predetermined value when said heat responsive means is in the run position and said first switch is open, said pressure switch opens causing a deenergization of the main and pilot valve opening means and a closureofthe main and pilot valves so that said pressure switch cannot reclose until said heat responsive'means returns to the start position to close said first switch and reopen said pilot valve.

2. In a fluid fuel burner control system, a main burner connected to a fuel supply source by a main burner conduit, a normally closed valve .interposed in said main 'bumerconduit. a pilot burner connected to said fuel supply source by ated opening means for the burner valve, electrically actuated opening means for the pilot valve, means for igniting said pilot burner, aswitching device having a set of normally open and a set of normally closed contacts, means dependent on the occurrence of combustion at said pilot burner for actuating said switching device to close said normally open contacts and to open said normally closed contacts, a normally open pressure switch, means for closing said pressure switch upon attainment of a predetermined pressure in the pilot conduit between said pilot valve and said pilot burner, an energizing circuit to which said pilot valve opening means is connected, said energizing circuit having a portion comprising two parallel paths, one of said paths including the normally closed contacts of said switching device and the other of said paths including said pressure switch, said main burner opening means being connected in parallel with said pilot burner actuating means by a circuit including the normally open contacts of said switching device.

3. In a fluid fuel burner control system, a m burner connected to a fuel supply source by a main burner conduit, a normally closed valve- -interposed in said main burner conduit, a pilot burner connected to said fuel supply source by I a pilot conduit, a normally closed ilot valve interposed in said pilot conduit, electrically actu-' ated opening means for the burner valve, elecpilot burner for-actuating said switching device to close said normally open contacts a'ndto open said first and second normally closed contacts, a normally open pressure switch, means for closing said pressure switch on the attainment of a predetermined pressure in the pilot conduit between the pilot valve and the pilot burner, an

energizing circuit to which said pilot valve opening means is connected, said energizing circuit having a portion comprising two parallel paths, one of said paths including the first normally closed contacts of said switching device and the other of said paths including said pressure switch,

said main burner opening means being connected in parallel with said pilot burner opening means by a circuit ,.including-the, normally open con tacts of said switching device and said electrically operated igniter being connected in parallel with said pilotburner opening means by a circuit including the second normally closed contacts of said switching device.

4. In a fluid fuel burner control system, a fuel burner, a conduit interconnecting said burner and a source of fuel supply, a normally closed valve interposed in said conduit, electrically actuated means for opening said valve, an energizing circuit for said valve actuating means, a first switch in said energizing circuit, a holding circuit shunting said first switch, said holding circuit including a second switch, means for operating said second switch in accordance with the fuel pressure in the conduit between said valve and said burner, igniting means for said burner, and means responsive to combustion at said switch.

burner for controlling said igniting means and said first switch.

5. In a fluid iuel burner control system, a fuel burner, a conduit interconnecting said burner and a source of fuel supply, a normally closed valve interposed in said conduit, electrically actuated means for opening said valve, an energizing circuit for said valve actuating means, a first switch in said energizing circuit, a holding circuit shuntlng'said first switch, said holding circuit including a second switch, means for operating said second switch in accordance with the fuel pressure in the conduit between said valve and said burner, and means responsive to combustion at said burner for controlling said first ssmim. J. LEVINE.